Room thermostats



June 22, 1965 M. M. GRAHAM ETAL 3,190,933

ROOM THERMOSTATS} Filed Nov. 5, 1962 I 9 Sheets-Sheet 1 I INVENTORS.

. MARVIN u. GRAHAM JOHN v1 WRIGHT y RALPH E. onuuuouo 77 M um, @6 41),Ma.

ATTORNEYS 1 M. M. GRYAHAM ETAL 3,190,988

June 22, 1965 ROOM THERMOSTATS 9 Sheets-Sheet 2 Filed Nov. 5, 1962 FIG.4

Fl G. 6

INVHVTORS MRWN H. GRAHAM ATTORNEYS 8 JOHN w. mam

Y RALPH E. muuuouo June 22, 1965 M. M. GRAHAM ETAL 3,190,933

noon wnnauosuws Filed Nov. 5, 1962 9 Shuts-Sheet 3 INVENT 5. MARVIN M.GRA M JOHN W. WRIGHT By RALPH E. onurmoun 71%, am, 436 4 zw A TTORNE Y5.

M. M. GRAHAM ETAL 3,190,988

June 22, 1965 ROOM mmosm'rs 9 Sheets-Sheet 4 Filed Nov. 5, 1962INVENTOR-S'.

MARVlN RAHAM JOHN VI. GHT BY RALPH E. DRUMMOND ATTORNEY June 22, 1965 M.M. GRAHAM ETAL 3,190,988

ROOM THERMOSTATS Filed Nov. 5, 1962 9 Sheets-Sheet 5 gl 33s IN VEN TORS.

MARVIN M. GRAHAM JOHN W. WRIGHT RALPH E. DRUMMOND A TTORNEYS.

June 22, 1965 M. M. GRAHAM ETAL 3,190,938

ROOM THERMOSTATS Filed Nov. 5, 1962 9 Sheets-Sheet a FIG. I6 FIG. |7

FIG. I8

INVENTOR-S. 445 MARVIN M. GRAHAM JOHN W. WRIGHT RALPH E. DRUMMOND ATTORNE Y6.

.June 22, 1965 M. M. GRAHAM ETAL ROOM THERMOSTA'IS 9 Sheets-Sheet '7Filed Nov. 5, 1962 INVENTORS. MARVIN M. GRAHAM JOHN W. WRIGHT BY RALPHE. DRUMWND v hlbul, a

- ATTORNEYJ.

June 22, 1965 M. M. GRAHAM ETAL 3,190,988

ROOM THERMOSTATS 9 Sheets-Sheet 8 Filed Nov. 5, 1962 INVENTORS MARVIN MGRAHAM BY JOHN W. WRIGHT R flaw ALPH E. DRUMMQND 4 3 A TTORNE YS June 221965 M. M. GRAHAM: ETAL 9 Sheets-Sheet 9 Filedi NOW. 5, 1962 FIG. 27

FIG. 29

FIG. 28

INVENTORS MARVIN M. GRAHAM JOHN W WRIGHT RALPH E. DRUMMOND ATTORNEYSUnited States Patent 3,190,988 ROUM THERNIOSTATS Marvin M. Graham, SanPedro, John W. Wright, Long Beach, and Ralph E. Drummond, Bell, Califi,assignors to Robertshaw Controls Company, a corporation of DelawareFiled Nov. 5, 1962, Ser. No. 235,915 20 Claims. (Cl. 200-122) Thisapplication is a continuation-in-part of copending application SerialNo. 176,282, now abandoned, filed February28, 1962. r

This invention relates to condition responsive control devices and moreparticularly to thermostats for controlling heating and cooling systems.

It is an object of this invention to provide a series of thermostatshaving interchangeable parts and components for adaptation with a wideselection of heating and cooling systems.

A further object is to provide a thermostat subassembly which is capableof interchangeable use as a component of several thermostats.

Another object is to provide a thermostat sub-base of integral, ruggedconstruction having supporting elements so arranged as to be capable ofsupporting a wide variety of arrangements of thermostat components.

Still another object is to provide a thermostat subassembly including abimetal actuated switch in which the bimetal may be accuratelycalibrated with respect to the switch.

A further object is to provide a thermostat that can be connectedelectrically to control both a heating and cooling circuit as desiredwithout the necessity of rearranging the operating parts of thethermostat.

An additional object is to provide a thermostat sub-base havingintegrally formed supporting elements located so as to support severaldifferent arrangements of thermostat components.

In achievement of the objects of the invention a base member ofinsulating material is provided having a pair of switch positioningbosses, an armature ledge, a spring support abutment, and mounting lugsintegrally formed thereon. In one form of the invention, a sleeve memberis rotatably received on a post which is secured to the base member.Mounted on the sleeve member is a cam follower which is frictionallyrestrained against rotation relative to the sleeve member and is biasedinto engagement with a cam which is rotatably secured to the basemember. Connected at its inner end with the sleeve is a spiral bimetalelement carrying a movable switch contact for operating an electricalcircuit in response to ambient temperature changes. The movable contactcarried by the bimetal cooperates with a fixed contact mounted on abracket member which is located in abutment with one of the switchpositioning bosses. For causing snap action of the switch contacts thefixed contact assembly comprises a permanent magnet and a screw contactreceived in the magnet and supporting bracket which is adjustable tovary the response of the switches to temperature change. Rotation of thecam adjusts the position of the bimetal relative to the fixed contact toincrease or decrease the temperature at which the switch contacts willclose. For calibrating the bimetal relative to the fixed contact, thecam follower may be selectively rotated against the frictionalengagement with the sleeve to adjust the angular position of the bimetalrelative to the fixed contact.

In another form of the invention, a permanent magnet is carried by thefree end of the bimetal and a magnetically responsive enclosed switch issupported on the switch positioning bosses for controlling either aheating or cooling system in response to the action of the bimetal.

3,190,988 Patented June 22, 1965 A third form of the invention includesa variable heat anticipating resistor rotatably mounted on the basemember beneath the post which supports the bimetal. The variableresistor provides a uniform distribution of temperature across thebimetal when the switch contacts are closed, and the base member ismounted on a wall plate having terminals for connection with both aheating and cooling control circuit. a

In a fourth embodiment of the invention a wall plate is provided for thebase member with a system switch and a fan switch having terminals forconnection with a cooling system and a heating system so that thethermostat can be selectively connected with either circuit to controlheating or cooling.

In still another form of the invention, the bimetal element is connecteddirectly with a post which is rotatable relative to the base. A camfollower mounted on the post is frictionally restrained against rotationrelative to the post by a spring washer. A novel anti-torque washercooperates with the variable resistor to prevent changes in resistorsettings when the thermostat setting is changed.

Other objects and adavntages of the invention will become apparent fromthe following description taken in connection with the accompanyingdrawing in which:

FIG. 1 is a front view of a thermostat embodying one form of theinvention;

FIG. 2 is a sectional view of the dial and cover assembly of FIG. 1 withthe base member and operating parts of the thermostat indicated inphantom lines; 1

FIG. 3 is a plan view of the base member of the thermostate of FIG. 1;

FIG. 4 is a back view of the base member of FIG. 3;

FIG. 5 is a perspective view of the temperature sensing element;

FIG. 6 is a sectional view taken on line 66 of FIG. 4;

FIG. 7 is a detailed sectional view taken on lines 77 of FIG. 4;

FIG. 8 is a plan view of the base member embodying a second form of theinvention;

FIG. 9 is a back view of the base member of FIG. 8;

FIG. 10 is an end view taken on lines 10-10 of FIG. 8;

FIG. 11 is a plan view of the base member embodying a third form of theinvention;

FIG. 12 is a back view of the base assembly of FIG. 11;

FIG. 13 is a plan view of a wall plate of the embodiment of FIGS. 11 and12;

FIG. 14 is a back view of the wall plate of FIG. 13;

FIG. 15 is a detailed sectional view taken on lines 1515 of FIG. 13;

FIG. 16 is a plan view of a thermostat embodying the invention in stillanother form;

FIG. 17 is a side view, partially in section, of the thermostat of FIG.16;

FIGS. 18 through 23 are schematic wiring diagrams of the thermostat ofFIGS. 16 and 17;

FIG. 24 is a view corresponding to FIG. 3 of the invention embodied inanother form;

FIG. 25 is a plan view of the base member of FIG. 24 with a sealedmagnetic switch;

FIGS. 26-28 are fragmentary plan views illustrating the assembly of thebimetal post and variable heat anticipating resistor for the embodimentof FIG. 25; and

FIG. 29 is a perspective view of a flexible cutoff lever.

Referring first to the embodiment illustrated in FIGS. 1-7, thethermostat is illustrated generally at 10 in FIG. 1, and includes acover member 12 in the form of a shell of plastic or other insulatingmaterial, a dial 14 rotatably supported on the cover member, and a basemember 16 which is frictionally received in the cover member andsupports the operating parts of the thermostat. As shown in FIGS. 3 and4, base member 16, which is also of plastic insulating material, has afront, substantially flat face 18,

3 and a rear face which is depressed to define a peripheral ridge 22.

Formed along the lower edge 17 of base member 16 is a pair of laterallyspaced switch positioning bosses 26 which are substantially L shaped incross section for 10- cating and supporting the thermostat switch on thefront face of base member 16. Intermediate the ends of lower edge 17 ofbase member 16 is an apertured lug 27, the aperture of which receives arivet for mounting a switch contact support bracket in a manner to bedescribed below. One end of lower edge 17 projects outwardly to define amounting lug 28 having a recessed slot 29 for receiving a mounting screw36 for mounting the base member on a wall or other supporting structure.Slot 29 extends through an oblong boss 32 projecting from the rear sideof base member 16 (FlG. 4). Formed adjacent the left edge 33 of basemember 16 is a recess 34 concentric with a boss 35 on the rear side ofthe base member (FIG. 4) having a threaded hole for receiving a mountingscrew 36. When base member 16 is mounted on a support, slot 29 permitsthe base member to be adjusted angularly about screw 36 before screw 36is tightened.

Integrally formed adjacent the right edge 37 of base member 16 is arectangular armature ledge 38 which projects perpendicularly from frontface 18 and serves as a limit stop for a movable armature on the end ofthe bimetal in one form of the invention, and also serves as a supportfor an auxiliary armature in another of the invention as will bedescribed presently. Also integrally formed on the base member andspaced inwardly from the corner formed by the upper edge 39 and rightedge 37, is a spring support 49 projecting from front face 18 andprovided with a notch 41 for receiving the end of a cam follower spring.

Spaced inwardly from edge 33 and formed integrally with the base memberis a hub 42 which receives the enlarged end 43 of a post 44. Enlargedend portion 43 is provided with a groove 45 for receiving a washer 46which in cooperation with a flange 47 formed on post 44, clamps the basemember between the flange 47 and washer 46. Post 44 is prevented fromrotating relative to the base member by a staking operation.

Rotatably received on post 44 is a sleeve member 418 having an adjustingnut 49 formed at one end which is provided with a circular shoulder 59.Shoulder 54 receives the apertured end of a cam follower 51.

concentrically mounted on sleeve 48 is a second, outer sleeve 52 whichis staked to sleeve 48 so that the sleeves rotate as a unit on post 44.The lower end of outer sleeve 52 is spaced from shoulder and a springwasher 53 is mounted between the lower end of sleeve 52 and cam follower51 to frictionally restrain cam follower 51 against rotation relative tosleeve members 48 and 52. To compensate for tolerance variations, aspacer washer 54 and a bowed spring washer 55 are received on post 44between the lower end of adjusting nut 49 and flange 47. Sleeve members48 and 52 are maintained in position on post 44 by a washer 56 incooperation with a cotter pin 57 mounted on the outer end of post 44.

Supported on the outer sleeve 52 is a bimetal element 58 for actuatingthe thermostat switch in response to temperature variations. Bimetal 58has its inner end spot-welded to the outer sleeve 52. 'Diametricallydisposed relative to hub 42 and post 44 isan elongated rectangulardepression 59 for securing a variable heat anticipating resistor to thebase member in another form of the invention as will be fully describedbelow. Depression 59 is concentric with a boss 60 formed on the rearface of base member 16.

Formed on rear face 29 of base member 16 is a circular boss 61 (FIG. 7)which is spaced from post 43 toward edge 17. Circular boss 61 isprovided with a shoulder 61:: (FIG. 7). Rotatably received in boss 61 isa cam shaft 62 having a shoulder or flange 63 formed intermediate itsends for cooperation with front face 18 of the base member, and a groove64 is provided adjacent the lower end of shaft 62 for cooperation withan open-sided spring E-washer 65 to secure shaft 42 to the base member.Shaft 62 is chamfered at its upper end and is provided with a fiat 66for cooperation with the hub of dial 14 for rotating shaft 62 with thedial.

Press fitted onto flange 63 for rotation with shaft 62 is a cam 68 fortransmitting the rotation of dial 14 and shaft 62 to cam follower 51.Cam 68 overlies front face 18 of base member 16 and is provided with atab 69 for cooperation with an arcuate temperature scale 70 formed onfront face 18.

Referring to FIG. 5, which illustrates the bimetal and cam followerassembly, cam follower 51 includes a lever arm 71 having a bifurcatedend 72, a spring aperture 73, and a cam follower tab 74 bent at rightangles to the inner end of lever 71 for engaging the surface of cam 68.For biasing cam follower tab 74 into engagement with the surface of cam68, a spring 75 (FIG. 3) has one end received in notch 41 of springsupport 40, and its other end received in aperture 73 on lever arm 71.Thus, as shaft 62 is rotated, cam 68 acts against cam follower tab 74 toshift cam follower 51 about post 43, and spring washer 53 transmits therotation to bimetal element 58 through sleeves 43 and 52. Forcalibrating the position of camfollower 51 relative to cam 68, arectangular groove 72a is formed in face 18 for receiving a tool whichmay be inserted in the bifurcated end portion 72 to hold cam follower 51stationary while sleeves 43 and 52 are rotated on post 44.

Bimetal 53 has its free end bent radially outwardly and an armature bar'76 is secured to the free end by a rivet 77 which also secures one endof a spring leaf contact 78 to the armature bar. Armature bar 76 isprovided with a slot 79 and a stop tab 80 is bent away from the slot tolimit the movement of leaf contact 78 outwardly from armature bar 76.

Referring to FIG. 3, a bracket 82 is mounted on front face 18 forsupporting a fixed contact. Bracket 82 is provided with a mounting lug83 for cooperation with lug 27 and a rectangular mounting tab 84 whichis positioned adjacent one of the switch positioning bosses 26. Rivets85 secure bracket 82 to the base member. Bracket 82 is provided with anupturned flange 86 for supporting a permanent magnet 87. Magnet 87 isformed with a threaded eyelet 88 which is inserted through an opening inflange 86, and a flange 89 formed on eyelet 88 secures the magnet inposition on the bracket. Eyelet 88 receives a contact screw 90 having acontact portion 91 for engagement with contact leaf 78 on the bimetalelement. Advancing screw contact 9% in eyelet 88 increases the distancefrom the magnet at which the contacts 78 and 91 close. This lowers thetemperature differential between opening and closing of the contactssince less force is required to separate the contacts as the distancefrom the magnet to the point of contact is increased. Due to theresiliency of contact leaf 78', a sliding or wiping contact ismaintained between fixed contact 91 and leaf contact 78 up to the pointof separation. Moreover a sliding contact occurs as the contacts closedue to the resiliency of contact leaf 78 minimizing the possibility ofarcing caused by rebound as contact is established. As' the bimetal 58cools, armature bar 76 moves toward permanent magnet 87 until themagnetic attraction overcomes the resiliency of bimetal element 58 andcauses the contacts to close with a snap action. Upon heating of bimetal58, contact is maintained due to the magnetic attraction between magnet87 and armature bar 76 until the contacts separate with a snap action.Movement of armature bar 76 away from magnet 87 is limited by armatureledge 38.

As shown in FIGS. 4 and 7, a night off control arm 94 is rotatablyreceived on circular boss 61. Control arm 94 has an enlarged aperturedend portion 95 which is received on boss 61 and seated against shoulder61a. End portion 95 is struck away at its peripheral portion to define atab 96 which extends at right angles to the control arm, and projectsthrough an arcuate slot 97 in the base member into the path of armaturebar 76. Control arm 94 may be rotated to a position in which tab 96prevents closure of the switch contacts to provide a night off controland prevent the heating system from operating when the building or spaceis unoccupied. Control arm 94 is maintained in position on boss 61 bythe cooperation of a retaining screw 98 with an arcuate slot 99 incontrol arm 94. Screw 98 is mounted in a threaded boss 100 projectingfrom the rear face 20, and the head of the screw prevents arm 94 frombeing displaced axially with respect to boss 61, but permits rotation ofarm 94 within the extremities defined by slot 99.

Formed on ridge 22 adjacent the lower edge 17 of the base member (FIG.4) is a raised rectangular boss 101 which cooperates with a bead 102formed in control arm 94 to maintain the setting of control arm 94 atthe extremities of its arcuate movement due to the resiliency of thematerial of control arm 94. The resilient engagement of bead 102 withboss 101 also serves to maintain the intermediate settings of controlarm 94.

Illustrated diagrammatically in FIG. 3 is a fixed resistor 105 ofconventional construction which is positioned adjacent to bimetal 58 andis secured to the base member by a screw 104. Resistor 105 is providedwith a connector 103 and is connected in series with bracket '82 by aconductor 106 to serve as a heat anticipator when the switch is closedto prevent overshooting of the furnace controlled by the thermostat dueto the time lag between ambient temperature rise and furnace operation.

Mounted on the rear face 20 (FIG. 4) are two terminal screws 107 and 108having terminal clips 109 and 110, respectively, for connecting thethermostat with the lead wires from an electrically operated valve orthe like which controls the furnace. Screw 104 serves to secure aterminal clip 111 to the rear face of the base member which iselectrically connected by a conductor 112 to terminal clip 110. Terminalclip 109 is connected by a conductor 113 with bimetal 58, conductor 113passing through an opening beneath notch 41 in spring support 40 and issoldered or welded to sleeve member 52. The conductors and terminalclips are all properly insulated and the conductors are connected by acombination of mechanical pressure and soldering.

FIGS. 1 and 2 illustrate the cover and dial assembly of the thermostatin which cover member 12 is provided with a circular boss 114 having ashoulder 115. Rotatably received in the opening of boss 114 is the hub116 of dial 14, and a spring washer 117 engages the inner end of the huband the periphery of the opening to resiliently maintain dial 14 inplace on the cover. Spring washer 117 rotates with hub 116. Hub 116 isprovided with a cylindrical opening having a fiat wall which cooperateswith the flat portion 66 of cam shaft 62. Cover member 12 is providedwith an arcuate groove 119 which cooperates with tab projection 120 atthe periphery of dial 14 to provide stops at maximum and minimumsettings within the operating range of the thermostat.

Adhesively attached to the front of cover member 12 is a foil scaleplate 121 having appropriately spaced temperature markings which arevisible through the transparent dial 14. Dial 14 is provided with araised convex portion 122 to magnify the temperature markings for bettervisibility. Convex portion 122 is provided with a temperature indicatingmark 123 for cooperating with the temperature markings on the front ofthe cover member. Concentrically mounted on boss 114 is a second spiralbimetal 124 having its inner end secured to the boss and having apointer 125 formed on its free end to indicate the ambient temperature.

Cover member 12 receives base member 16 through its open back withnotches 126 cooperating with projections 127 (FIG. 3) to maintain apressfit engagement between the cover and base member. Rectangularopenings 18 in the side walls of the cover member permit free flow ofambient air beneath the cover for bimetal 58, and also to provide anopening through which control arm 94 extends from the cover to beaccessible for manual operation. Rotation of dial 14 acts through camshaft 62 to increase or decrease the temperature at which contacts 70and 91 will close. Base member 16 (FIG. 3) is provided with an arcuateslot 130 beneath the tab 69 of cam 63 into which may be insertedadjustable stop screws 132 (FIG. 11) to provide maximum and minimumtemperature settings for cam 68. The temperature indicating marks ofscale 70 correspond to the positions of cam 68 and dial 14.

To calibrate the thermostat, it is placed in a controlled temperaturewithin the operating range of the thermostat. Tab 69 of cam 68 ispositioned at the indicating mark on scale 70 corresponding to thecontrolled temperature. A screw driver blade is then inserted into thebifurcated end 72 of cam follower lever 71 and the cam follower ismaintained stationary by engagement of the screw driver blade with notch72a. Sleeves 48 and 52 are then rotated on post 44 against thefrictional resistance of spring washer 51 to move bimetal 58 to aposition such that switch contacts 91 and 78 just close at thecontrolled temperature.

Clockwise rotation of cam 63 acts through cam follower 51 to causeclockwise rotation of bimetal 58 on post 44 (as viewed in FIG. 3). Thiscauses armature bar 76 to move further away from contact 91 requiring alower temperature to actuate the switch. As the ambient temperaturedecreases, bimetal 58 deflects to move armature bar 76 and spring leafcontact 78 toward the magnet until the force of magnetic attractionovercomes the resiliency of bimetal 58 and causes the contacts to closewith a snap action. Cam 68 is designed so that the amount of bimetaldeflection per degree of temperature change corresponds to the angularrotation of shaft 62 and cam 68 between the different temperaturesettings on scales 121 and 70. Thus, the temperature indicated at 123 isthe temperature at which the contacts will close.

When contacts 78 and 91 close, the current path is as follows: fromterminal 107 through conductor 113 to bimetal 58, from bimetal 58through contacts 78 and 91 to bracket 82, from bracket 82 throughconductor 106 to the heat anticipation resistor 105, and from resistorthrough screw 104, terminal clip 111 and conductor 112 to terminal clip110.

Resistor 105 is heated when energized by the switch to increase thetemperature at the bimetal to cause the switch contacts to separateslightly before the ambient temperature reaches the temperature settingso that the ambient temperature will not increase above the temperaturesetting due to the lag between the ambient temperature rise and furnaceoperation.

In a typical installation, base member 16 is mounted on the wall of theroom or space to be heated by means of screws 30 and 36 and anelectrically operated gas valve is connected in series with terminals107 and 108 of the thermostat. When the thermostat is set to provide atemperature above the ambient air temperature, the bimetal defiects toclose the switch contacts 78 and 91 to complete the circuit, and the gasvalve is actuated to start the furnace into operation. Current flowsfrom bracket 82 to resistor 105 which generates heat adjacent to thebimetal in addition to the ambient air temperature to compensate for thelag in ambient air temperature as sensed by the thermostat so as toavoid over-shooting the temperature setting. When the requiredtemperature increase results in an attained temperature at the bimetalequal to the setting temperature plus the temperature difierential(approximately 2 degrees to 3 degrees Fahrenheit) of the switch ascontrolled by the setting of contact 91, the switch contacts open due tothe heating of bimetal 58, shutting off the gas valve to the furnace.Opening of the switch contacts also deenergizes the anticipator resistor105 as it is in series with the switch. Upon subsequent cooling of thebimetal, the switch contacts close when the set temperature is reachedand the operating cycle is repeated.

Illustrated in FIGS. 8, 9, and 10 is a second embodiment of theinvention in which the base member supports a different arrangement ofcomponents. Identical structure to that of the first embodiment isidentified in FIGS. 8-10 by the same reference numerals.

In the embodiment illustrated in FIGS. 8-10, bimetal element 58 carriesat its free end a permanent magnet 200. Slidably mounted on armatureledge 38 is a U- shaped auxiliary armature clip 202 (FIG. 10) to providean adjustable temperature differential. Auxiliary armature 202 isadjusted laterally on ledge 38 to provide the desired temperaturedifferential, after which it is sealed in place by resinous sealingmaterial.

Mounted on the L-shaped switch positioning bosses 26 is a glass enclosedmagnetically responsive switch 204. Switch 204 is of the type disclosedin the copending application of John C. Hewitt, In, Serial No. 54,620,filed September 8, 1960, now patent No. 3,068,333, granted on December11, 1962, and assigned to the assignee of this invention. Switch 204 isa glass enclosed, but unsealed version of the switch disclosed in theabove referred-to copending application, and is provided with anon-magnetic dust cap 206 which is press-fitted over the open end of theswitch 204. For securing switch 204 on base member 16, a hooked springclip 208 is mounted in a slot 209 in the base member, and switch 204 isreceived in the hooked portion of the spring clip and resilientlymaintained in position on bosses 26.

As is fully disclosed in the above referred to copending application,switch 204 is provided with a pair of fixed contacts which are connectedwith terminals of separate circuits, and a movable contact connectedwith a terminal common to both of the circuits. The movable contact isspring-biased into engagement with one of the fixed contacts and isactuated in response to magnetic flux to snap closed against the othercontact. In the thermostat of FIG. 8, the movable contact of switch 204is biased against a fixed contact which is connected with a coolingconductor 212. Cooling conductor 212 is not connected to a controlcircuit since the thermostat is illustrated in FIG. 8 as a heatingcontrol only. Switch 204 has its other fixed contact connected to aheating conductor 210 for controlling a heating system, and the movablecontact is connected to a power conductor 214 which is to be connectedto a power source.

When bimetal 58 is heated, it deflects to move magnet 200 intoengagement with auxiliary armature 202 and the movable contact of switch204 moves to the cooling position, but since conductor 212 isdisconnected, no current can flow to the thermostat. This is the heatingoff position of switch 204.

When bimetal 58 cools, magnet 200 is moved adjacent switch 204 causingthe movable contact to snap to the heating on position connecting powerconductor 214 with heating conductor 210. With terminal screws 107 and108 connected in series with a furnace control, a current path isprovided from terminal clip 109 (FIG. 9) through conductor 214 to switch204, from switch 204 through conductor 210 to heat anticipating resistor105 and terminal clip 111, and from terminal clip 111 through conductor112 to terminal clip 1110. Except for the use of the glass enclosedswitch 204 and auxiliary components just described, the operation,calibration and glass housing which is gas filled. Switch 304- isconnected with a heating conductor 310 and a cooling conductor 312 withthe movable contact connected to a power conductor 314.

Mounted on post 43 beneath sleeve 48 is a variable heat anticipatingresistor 316. Resistor 316 is of the type disclosed in the copendingapplication of John C. dewitt, Jr., Serial No. 148,283, filed October27, 1961, now Patent No. 3,147,354, granted on September 1, 1964, andassigned to the assignee of this invention. The latter Hewittapplication discloses a resistance coil holder rotatably mounted forcooperation with a pair of fixed, congruent contact wipers for varyingthe resistance between the contact wipers upon rotation of the coilholder. An elongated leaf spring biases the coil holder into engagementwith the contact wipers. Another embodiment disclosed in the sameapplication concerns a fixed coil mounted in a base member forcooperation with a rotatable wiper blade having contact surfaces forcooperating with the resistance coil to vary the number of coils betweenthe contact surfaces when the wiper blade is rotated relative to theresistance coil. In FIG. 11, an arm 318 is connected withthe movableelement of the variable resistor and cooperates with an arcuate scale320 formed on the base member 16 which provides amperage markings bywhich the resistor settings corresponding to switch loading can be made.

The embodiment of FIGS. 11 and 12 is adapted for use as both a heatingand cooling control and the control arm 94 has been omitted. However,control arm 94 may be included when the thermostat is operating tocontrol a heating system.

In the embodiment of FIGS. 11 and 12, base member 16 is mounted on awall plate 322 illustrated in FIGS. 13, 14, and 15. Wall plate 322 isprovided with a substantially fiat front face 323 and a back face 324(FIG. 14) which is recessed to define a peripheral ridge 32.5. Mountedon the front face 323 of wall plate 322 are three stepped terminalconnectors 326, 327' and 328. As shown in FIG. 15, terminal connector328 is seated on a stepped boss 329 having openings 330 and 331 forreceiving cylindrical projections 332 and 333 which are provided withinternally threaded holes334 and 335, respectively. Cylindricalprojection 332 extends from an upper portion 328a and cylindricalprojection 333 extends from a lower portion 328b. Portions 328a and32812 are connected by a vertical portion 328a. Mounted in the threadedhole 335 is a terminal screw 336 which secures a terminal clip 337 tothe connector 328 for electrical connection with the lead wire from acooling relay.

Connector 328 is secured to wall plate 322 by bentover tabs 338 whichcooperate with an opening 339 and a notch 340 in the wall plate, thetabs being received in a recess 341 formed on the back face of the wallplate. Connectors 326 and 327 are identical in construction to connector328 and are provided with terminal screws 342 and 343, respectively, andthreaded holes 344 and 345, respectively, for receiving contact screwsfrom base member 16 in a manner to be described below.

Pormed on the back face 324 of wall plate 322 is a cylindrical boss 345which is concentric with a cylindrical depression 347 on the front face323 for receiving hub 42 and the end of post 44 when base member 16 issecured to the wall plate. An opening 348 is provided in the wall platefor access to the wires from the wall which are to be connected toterminals 326, 327 and 328. Semi-circular grooves 349 and 350 are formedon the side edges of'wall plate 322 for accommodating bosses 35 and 32,respectively, of base member 16. Provided on the back face 324 is a boss351 having a slotted recessed opening 352 which receives a mountingscrew 353 for securing wall plate 322 to a wall. A second mounting boss354 is provided adjacent the opposite corner of the wall plate forreceiving a mounting screw 355.

Again referring to FIG. 12, two terminal clips 359 and 360 are securedto bosses 361 and 362, respectively, by rivets 363 and 364. Terminalclips 359 and 360 are provided with apertured cup-shaped portions whichare positioned over the holes in bosses 361 and 362, and captive screws365 and 366 are mounted in the cup-shaped portions, with the screw headsbeing received in the recessed openings on the front face of base member16 (FIG. 11). Screws 365 and 366 are threadedly received, respectively,in holes 345 and 344 of terminal connectors 327 and 326 when the basemember is secured to wall plate 322.

Terminal clips 367 and 368 are riveted, respectively, to bosses 369 and370 (FFIG. 12) formed on the rear face 20 of base member 16. Screws 371and 372 are threadedly mounted in terminal clips 367 and 368,respectively. When base member 16 is mounted on wall plate 322, screw371 is received in threaded hole 346 of terminal connector 328, andscrew 372 is received in a threaded boss 373 formed on the front face323 of wall plate 322.

Conductor 314 from switch 304 passes through an opening inbase member 16and isconnected with terminal clip 359 ('FIG. 12). Cooling conductor 312from switch 304 extends through the same open-ing and is connected withterminal clip 367. Heating conductor 310 from switch 304 extends throughan opening in base member 16 and connects with one end of the resistacecoil of the variable heat anticipating resistor 316. The other end ofthe coil of heat anticipating resistor 316 is connected by a conductor374 with terminal clip 360. Terminal screw 342 (FIG. 13) electricallyconnects one end of the lead wire from an electrically operated gasvalve through opening 348 to connector 326. Terminal connector 327 isconnected with the lead wire from the main power source by terminalscrew 343, and connector 328 is connected with the lead wire from anelectrically operated relay for the cooling circuit by means of terminalscrew 336. For selecting the circuits for heating operation, coolingoperation, or complete off, an additional three-way switch ahead of thewall plate can be used.

As a heating thermostat, bimetal 53 deflects, upon cooling, to move thepermanent magnet 200 toward switch 304 until its movable contactelectrically connects conductors 310 and 314 to start .the furnace intooperation. The current path is as follows: the main power source isconnected with terminal 343 and current flows from terminal 343 throughconnector 327 and screw 365 to power conductor 3114, and throughconductor 314 into switch 304 to heating conductor 310, from heatingconductor 3110 through resistor 316 to conductor 374, and from conductor374 through screw 366 to connector 326 and terminal screw 342.

As a cooling thermostat,and assuming that the threeway switch is in theon position with respect to the cooling side of the three-way switch,the movable contact of switch 304 electrically connects coolingconductor 312 with power conductor 314 when permanent magnet 200 ismoved away from switch 304 due to heating of the bimetal 58. The currentpath is as follows: from terminal screw 343 through connector 327 andscrew 365 to power conductor 314, through cooling conductor 312 toterminal clip 367, from terminal clip 367 through screw 371 to connector328, from connector 328 to terminal screw 336 which is connected withthe lead wire from the cooling circuit. Heat anticipating resistor 316is inoperative when the thermostat operates as a cooling thermostat.

FIGS. 16 and 17 illustrate a fourth embodiment of the thermostat inwhich the base assembly of FIGS. 11 and 12 is combined with a covermember 400 and is mounted on a wall plate 401. Rotatably mounted oncover member 400 is a dial 402 which contains the same functionalcomponents as those described for the cover and dial assembly shown inFIGS. 1 and 2. Cover member 400 is provided on its front face with afoil scale plate 403 with switch position indicating markings asillustrated. Screws 372, 37 1, 365 and 366 (FIG. 11) are received inthreaded bosses on wall plate 401 for mounting base member 16 upon the'wall plate. For assisting in positioning base member .16 on wall plate401, a plurality of raised positioning bosses are formed on the wallplate, one such boss being illustrated at 4M (FIG. 17).

Wall plate 461 is provided with a bracket (not shown) for mounting adouble pole, triple throw, system control switch 405 and a single pole,double throw, fan control switch 406 which are illustrated schematicallyin FIGS. 18-23. Slide actuators 40 7 and 408 are provided respectivelyfor switches 405 and 406, and project through an appropriate opening incover member 400 as shown in FIG. 16. Dial 403 contains indicatingmarkings heat, off and cooling for the three positions of the controlswitch 405, and markings man (manual) and auto (automatic) for the twopositions of fan control switch Control switch 405 is provided withterminals 409, 410, 411, 412, 413, 414, 415, and 416, and fan controlswitch 406 is provided with terminals 417, 418, and 419. Terminals 41 1,413, and 4 15 of control switch 405 are connected by a shunt wire 420with terminal 417 of fan control switch 406. Terminal 411 of switch 405is connected by a conductor 422 to a power terminal 423 on wall plate401 which in turn is connected through an opening in wall plate 401 witha lead wire 424 from one side of the secondary of a transformer 425.Terminal 414 of control switch 405 is connected to terminal 419 of fanswitch 436 by a conductor 446.

Wall plate 40.1 is provided with terminal connectors 426, 427 and 428which are identical in construction and correspond, respectively, toterminal connectors 326, 327, and 328 of wall plate 322 illustrated inFIG. 13. Connected in series between terminals 427 and 428 is a fixed,cooling system heat anticipating resistor 421. Terminal connectors 426,427 and 428 are seated on raised bosses as in the previously describedembodiment of FIG. 13, one such boss 429 for terminal connector 428being illustrated in FIG. '17. Screws 366, 365, and 371 (FIG. 11) ofbase member 16 are threadedly received in connectors 426, 427 and 423respectively, to electrically and mechanically connect the terminalconnectors with the base member. Connector 427 is connected to powerterminal 423 by a conductor 43 1.

FIGS. 18-23 illustrate the operation of the thermostat of FIGS. 16 and17 in a typical installation. Wall plate 401 is provided with a heatingterminal 433, a fan terminal 434, and a cooling terminal 435. Through anopening in wall plate 401, heating terminal 433 is connected with a leadwire conductor 439 from a conventional control 443 such as a relay foravolt system, of a heatingcontrol circuit. Relay 440 controls a circuitwhich includes an electrically actuated fuel control valve or the likeso that when relay 440 is on, that is, when it is energized electricallyby the thermostat, the valve opens to start the furnace into operation.

Fan terminal 434 is connected through an opening in wall plate 401 witha lead wire conduct-or 442 from a fan circuit relay 443. Energization ofrelay 443 supplies power to a cooling fan which is normally providedwith a separate on-olf switch in the circuit so that the fan can beturned on or olf regardless of the thermostat setting. In a typicalsystem a separate fan control circuit would be provided to operate aheating fan in response to air duct temperature.

Cooling terminal 435 is connected with a lead wire conductor 444 from acooling circuit relay 445. Energization of relay 445 completes a coolingsystem control circuit to bring the cooling system into operation.

The movable contact of switch 308 is illustrated diagrammatically at308a in FIGS. l8-23. In FIGS. l8, l9 and 20, switch .303 is shown in theheating on position due to the thermostatic actuation of the switch bybimetal 58 and magnet 200. In FIGS. 18, 19 and 20, bimetal 58 is cooled,causing magnet 200 to move toward switch 308 and actuate contact 303a tothe heating position. Thus,

11 the thermostat is demanding heat in FIGS. l8, l9 and 20.

In FIGS. 21, 22 and 23, switch 398 is in the cooling on position withcontact Eitiiia electrically connecting power conductor 314 with coolingconduct-or 312. Contact 3178a snaps to the cooling position when magnet2% is attracted to auxiliary armature 2&2 upon heating of bimetal 58.

In FIG. 18, control switch 405 is the heat position and fan switch 4% isin the manual position. With switch 3&8 in the heating position, acircuit is completed to relay 44% to bring the furnace into operation.The circuit extends from the secondary of transformer 4-25 throughconductors 424, 431 and 314 to switch 3%; from switch 363 throughconductor 31%, the variable heat anticipating resistor 314i andconductor 43%? to terminal 412 of control switch 465; and from terminal412 through actuator 4-97, terminal 414?, and conductors and 439 toheating relay 440; and from relay i t-t3 and conductor 441 to the otherside of the transformer secondary. When contact Stlfia moves to thecooling position upon satisfaction of the thermostat, the circuit isbroken to the heating relay to shut down the furnace.

'In either position of switch 3%, a fan circuit is completed sinceactuator 4%, when in the manual position, connects terminal 418 withterminal 417, which in turn is connected with shunt wire 426 to providea circuit from the transformer secondary through conductor 424, and 422and shunt wire 42% to terminal 417; from terminal 417 through actuator4% to terminal 418; from terminal 418 through conductors 437 and 442,relay 443 and conductor 4 51 to the other side of the transformersecondary. Accordingly, the fan may be controlled by its on-off switchindependently of the thermostatically actuated switch 3%. Cooling relay4 .5 is off in either position of switch 3% with control switch 465 inthe heating position and fan switch 4% in the manual position.

With fan switch 406 in the auto position and control switch 4% in theheat position as shown in FIG. 19, the operation of heating relay 44% isthe same as in FIG. 18, but fan relay 443 and cooling relay 445 are bothoff in either position or" switch 3%.

In FIG. 20, control switch 495 is in the off position and fan switch4416 is in the manual position. Heating relay 449 and cooling relay 445are both off in either position of thermostat switch 368, and the fanrelay 443 is on in either position of thermostat switch 393 as in theFIG. 18 condition to permit fan operation for cooling without operationof the cooling system controlled by relay 445.

PEG. 21 illustrates the control switch 405 in the off position and fanswitch 466 in the automatic position with the result that heating relay440, fan relay 443 and cooling relay 445 are all oif in either positionof switch 303.

Control switch 4175 is in the cooling position in FIG. 22 and fan switch4% is in the manual position. When switch 308 is in the coolingposition, a cooling circuit extends from the transformer secondarythrough conductors 424, 451 and 314 to contact 3%:1 of the thermostatswitch; from switch 3% through conductors 312 and 432 to terminal 414 ofcontrol switch 465; from terminal 414 through actuator 4637 to terminal416 and through conductors 446, 438 and 444 to cooling relay 445, andfrom relay 445 through conductor 441 to the other side of thetransformer secondary. When switch Silt: moves to the heating position,the cooling relay is ofi. Fan relay 443 is on continuously in eitherposition of switch 308. The current bypasses fixed heat anticipatingresistor 421 due to its high resistance. Resistor 421 is therefore oil",or tie-energized at all times when fan switch 4% is in the manualposition. Heating relay 440 is off in either position of switch 563 whencontrol switch 4&5 is in the cooling position.

FIG. 23 illustrates the same condition for control switch 12 46 5, butfan switch 4% is in the automatic position to connect fan relay 443 inparallel with cooling relay 445. When switch 3i8is in the coolingposition, a current path is provided from the secondary of transformer:25 through conductors 424, 431 and 314, switch 3%, conductors 312 and432, actuator 407 and conductor 446 to terminal 419 of fan switch 4%,and from terminal 419 through parallel conductors 437 and 433 to the fanrelay 443 and cooling relay 445, respectively, to conductor 441 and theother side of the transformer secondary. An alternate current path isprovided through fixed resistor 421, but due to the high resistance ofresistor 421, it receives only a minimum amount of current and iseffectively shunted outwhen switch 3% is in the cooling position.

When switch 398 moves to the heating position in the conditionillustratedin FIG. 23, fan relay 443 and cooling relay 445 are in serieswith fixed resistor 421, and a circuit extends fromthe transformersecondary through conductors 424 and 431, resistor 421, conductor .432,actuator 487, conductor 446 and through the parallel conductors to thefan relay 443 and cooling relay 445 to the other side of the transformersecondary. However, the high resistance of resistor 421 preventssufficient current to flow to the fan and cooling relays, and sinceresistor 421 receives the full current load, it generates heat forbimetal 58 to operate as a cooling system heat anticipator. Thus, as theambient temperature approaches the set temperature of the thermostat,the heat generated by resistor 421 causes bimetal 58 to deflect to movemagnet 2% against auxiliary armature 292 and snapactuate 308a to thecooling position before the ambient temperature reaches the set point.This prevents the temperature from rising above the set point due t thelag in the cooling efiect of the cooling system after the thermostatswitch closes.

F163. 24 and 25 illustrate another form of the invention employingrespectively an open contact switch and a sealed magnetic switch.

Rotatably mounted on the base member 16' (FIG. 24) is a post 44 having ascrewdriver slot 44a at its upper end. A spring washer 53' is stakedagainst cam follower 51 to frictionally restrain the cam followeragainst rotation relativeto post 44. Cam follower 51 is biased intoengagement with cam 68' by spring 75 connected between the end of leverarm 71 and a spring support 41%.

Projecting from the front face of the base member 16 in the path oflever arm 71' is a stop post 5%. In order to lower the calibration, post44 may be rotated counter clockwise by engaging slot 44a with ascrewdriver. Lever arm 71' will strike stop post 5% and continuedcounter clockwise rotation will cause slippage between the post and camfollower to lower the calibration.

To raise the calibration, post 4-4 is rotated clockwise and cam follower51 is held stationary against cam 68' or a tool positioned in the pathof lever arm 71, so that the resulting slippage will increase thecalibration. In FIG. 24, the switch contacts 78 and 91' are enclosed m ahousing5ti2 of transparent plastic material. Magnet 87 is mounted on abracket 22 with fixed contact 91' provided with a screwdriver slot foradjustment, and a locking nut 91a. Cam differs from cam 68 previouslydescribed in that an indentation is provided in tab 69 to resilientlyengage the temperature scale To ensure snap opening of the switchcontacts upon satisfaction of the thermostat, and to break contactbetween the movable contact and magnetic field of magnet 87, a cut-offlever SM is mounted on the rear face of base member 16'. Cut-off lever5% is shown in detail in FIG. 29 and comprises an enlarged apertured lugportion 5536 for securing the lever to the rear face of the base member.Projecting at substantially a right angle from lug portion 536 is aresilient arm member 5%. Arm member 5% extends through slot 97'. For theopen contact switch of the shape.

type illustrated in FIG. 24 an extension 510 projects from the end ofarm member 508 and engages armature bar 76 at the free end of thebimetal. When the switch contacts are closed as. illustrated in FIG. 24,arm member 508 exerts a biasing force on the movable contact tending toseparate the contacts. As soon as the set point temperature is reachedto satisfy the thermostat, the resilient force of arm member 508augments the force of bimetal 58 as it urges the contacts apart and thecontacts are opened with a snap action.

In the version of FIG. 24, a fixed heat anticipating resistor may beprovided with a connector 103 secured to the base member and having anenlarged apertured end portion received on post 44'.

In FIG. 25, the sealed magnetic switch 304 with the movable contact 398ais mounted on bosses 26' of base member 16 by a spring clip 208. Mountedon the end of switch 304 is a sleeve 512 of resilient material toeliminate noise produced by the snap engagement of magnet 200 with theswitch housing. Instead of auxiliary armature 202 on ledge'38, the freeend of the bimetal which carried magnet 200 is provided with anextension 514 having a bent tab 516 which cooperates with a stationaryarmature 518. Tab 516 may be bent in either direction to vary thespacing and thus the temperature differential. To eliminate the noise oftab 516 striking armature 51S, tab 516 is provided with sleeving 520.Arm member 508 of cut-off lever 504 urges the magnet 200 away from theswitch housing. However due to the change in spacing, extension 510 ofcut-off lever 504 is omitted from the FIG. 25 embodiment as indicated bythe broken lines of FIG. 29. As cam 68 is rotated counter clockwisetoward the off position, arm member 508 pushes the magnet away from theswitch and the cam follower may be locked in a notch 68a formed on cam68.

FIGS. 26, 27 and 28 illustrate the assembly of variable resistor 316,previously described with reference to the embodiment of FIG. 11, onbase member 16'. Fixedly mounted on base 16 on diametrically oppositesides of aperture 44a, is a pair of helically Wound coils 316a and 316b,as clearly disclosed in the latter referred to Hewitt application. Post44' is mounted in aperture 44a and a contact wiper blade 317 is receivedon post 44 (FIG. 27) having oppositely disposed crests defining wipercontacts 317a and 317b, which engage respectively the oppositelydisposed resistance coils 316a and 31Gb. As clearly disclosed-in thelatter referred to Hewitt application, rotation of wiper contact 317about post 44- varies the number of coils of resistors 316a and 3161;which are in contact with contacts 317a and 317b of the wiper contact.

In order to prevent undesired rotation of the rotatable contact 317 uponrotation of cam 68 or upon calibration of cam follower 51' with respectto cam 58', an anti-torque washer 524 is mounted on post 44' having anenlarged centrally apertured concave portion 526, the outer rim 528 ofwhich resiliently engages the rotatable wiper contact 317. Extendingradially from enlarged portion 526 is a locking leg 530 having a recess532 at its end for engaging stop post 500. Formed on post 44 is anenlarged shoulder 49 which is illustrated in FIG. 24 as being hexagonalin However, the hexagonal configuration is not necessary due to theprovision of slot 44a.

Shoulder 49' overlies concave portion 526 of 524 and resiliently biasesthe concave portion against contact 317 and restrains contact 317against rotation relative to post 44. Accordingly, if it is desired tochange the setting of resistor 316, arm 318 can be rotated about post 44against the frictional engagement of washer 524. However thiscalibration of the thermostat by rotating post 44' and cam 51 relativeto cam 68, can be accomplished without effecting the setting of resistor316.

While specific examples of the invention have been illustrated anddescribed, it will be understood that the invention is not limited tothe exact construction illustrated, and that various alterations andmodifications in the construction and arrangement of parts are possiblewithin the scope of the invention as defined by appended claims.

What is' claimed is:

1. A control device comprising;

a base member of insulating material,

electrical switch contacts on the base member,

a post rigidly secured to the base member,

an inner sleeve member rotatably received on the post having an enlargedadjustment nut formed at its lower end adjacent the base member,

a circular shoulder formed on the adjustment nut,

a cam follower received on the circular shoulder,

an outer sleeve member concentrically mounted on the inner sleeve memberand fixed against rotation relative to the sleeve member,

the lower end of the outer sleeve member being spaced from the circularshoulder,

a resilient spring washer mounted on the inner sleeve member between thecam follower and the lower end of the outer sleeve member forfrictionally restraining the cam follower against rotation relative tothe sleeve members, 1

a bimetal element secured at one end to the outer sleeve member with itsother end movable in response to ambient temperature variations foroperating the switch contacts,

and a cam rotatably mounted on the base member operatively engaging thecam follower for varying the temperature response of the bimetal member,

said cam follower and sleeve members being selectively rotatablerelative to each other for calibrating the position of the bimetalrelative to the cam.

2. A control device comprising:

a base member having a front face and a rear face,

a circular, apertured boss projecting perpendicularly from the rearface,

a shaft rotatably mounted in the aperture of the boss .and extendingperpendicularly from the front face,

a cam mounted on the shaft and overlying the front face,

a post rigidly secured to the base member and extending perpendicularlyfrom the front face,

an innersleeve rotatably mounted on the post with an enlarged adjustmentelement formed thereon,

a cam follower mounted on the inner sleeve against the adjustmentelement and biased into operative engagement with said cam,

an outer sleeve concentrically mounted on the inner sleeve and fixedagainst rotation relative to the inner sleeve,

the outer sleeve having one end spaced from the enlarged adjustmentelement,

a spring washer concentrically received on the inner sleeve between thecam follower and said one end of the outer sleeve to frictionallyrestrain the cam follower against undesired rotation relative to thesleeve members,

a fixed contact on the front face of the base member,

a bimetal element secured at one end to the outer sleeve,

a movable contact carried by. the free end of the bimetal element forengagement with the fixed contact in response to ambient temperaturechanges,

a control arm rotatably mounted on the circular boss and overlying therear face of the base member,

a slot in the base member,

and a stop tab on the control arm projecting through the slot into thepath of movement of the movable contact for selectively engaging themovable contact upon rotation of the control arm to prevent actuation ofthe fixed and movable contacts.

3. A control device as defined in claim 2 including: an arcuate slot inthe control arm radially spaced from the circular boss, anda retainingscrew having a stem extending through 1 5 the arcuate slot andthreadedly connected with the rear face of the base member,

the head of the retaining screw cooperating with said arcuate slot toprevent axial displacement of the control arm relative to the basemember.

4. A control device as defined in claim 2 including:

a heat anticipating resistor mounted on the front face adjacent thebimetal element,

first and second terminals on the rear face of the base member forconnection with a heating control,

a third terminal on the rear face in electrical engagement with the heatanticipating resistor,

a conductor connecting the fixed contact with the heat anticipatingresistor,

a conductor connecting the second and third terminals,

and a conductor connecting the bimetal element to the first terminal.

5. A control device comprising:

a base member of insulating material having a front face and a rearface, a

a post rigidly secured to the base member and projecting perpendicularlyfrom the front face,

:an inner sleeve member rotatably received on the post having anenlarged adjustment nut formed at its lower end adjacent the basemember,

a circular shoulder formed on the adjustment nut, a cam followerreceived on the circular shoulder,

an outer sleeve member concentrically mounted on the inner sleeve memberand fixed against rotation relative to the inner sleeve member,

the lower end .of the outer sleeve member being spaced from the circularshoulder,

a resilient spring washer mounted on the inner sleeve member between thecam follower and the lower end of the outer sleeve member forfrictionally restraining the cam follower against rotation relative tothe sleeve members,

an apertured boss projecting from the rear face of the base member,

a shaft rotatably mounted in the aperture of the boss and extendingperpendicularly from the front face,

a cam mounted on the shaft and overlying the front face, 7

a spring support on the front face of the base member,

a lever arm formed on the cam follower,

a spring having one end connected to the spring support and the otherend connected to the lever arm biasing the cam follower into engagementwith the cam,

electrical switch means mounted on the front face of the base member,

a ledge projecting perpendicularly from the front face,

and a bimetal element secured at one end to the outer sleeve,

the free end of the bimetal element being movable between the switchmeans and the ledgefor operating the switch means in response to ambienttemperature variations.

6. A control device as defined in claim 5 including:

a control arm rotatably mounted on theapertured boss and overlying therear face of the base member,

a slot in the base member, a Y

and a stop tab on the control arm projecting through the slot into thepath of movement of the freeend of the bimetal for selectively engagingthe free end of the bimetal to prevent actuation of the switch means.

7. A control device comprising:

a base member of insulating material,

a switch mounted on the base member including,

first and second fixed contacts,

a movable contact biased into engagement with the first fixed contactand magnetically responsive to engage the second fixed contact,

a cam rotatably mounted on the base member,

iii 1 a post rigidly secured to the base member,

a sleeve rotatably mounted on the post,

a cam follower mounted on the sleeve and biased into engagement with thecam,

an auxiliary armature member on the base member displaced from theswitch,

a spiral bimetal element secured :at one end to the sleeve and disposedin a plane parallel to the base,

and a magnet carried by the free end of the bimetal element for movementbetween the switch and the auxiliary armature in response to ambienttemperature variations to actuate the movable contact of the switchbetween the first and second fixed contacts.

8. A control device as defined in claim 5;

said switch means comprising,

first and second fixed contacts,

a movable contact biased into engagement with the first fixed contactand operative in response to magnetic attraction to engage the secondfixed contact, a

a magnet carried by the free end of the bimetal for alternatelyconnecting the movable contact with said first and second fixed contactsin response to ambient temperature variations,

and an auxiliary armature member mounted on said ledge.

9. A control device as defined in claim 7 including;

a resistor on the base member electrically connected in series with thesecond fixed contact of the switch for heating the bimetal element uponclosure of the movable contact with the second contact.

10. A control device as defined in claim 9;

said resistor including,

an element having an elongate resistance coil winding,

and an element having arcuately formed contact wipers rotatably relativeto the winding for variably engaging equal and oppositely disposedportions of the winding,

said winding being disposed in the plane of the base member with equalportions of the winding on opposite sides of said post,

one of said elements being rotatably mounted on said post independentlyof the sleeve,

and the other of said elements being secured to the base member andelectrically connected in series with the second fixed contact of theswitch.

11. A control device as defined in claim 10 including;

an indicating tab on the cam,

an arcuate slot in the base member in the plane parallel to the path ofrotation of the indicating tab,

and adjustable stop screws in the arcuate slot for selectively limitingthe angular rotation of said cam.

12. A control device comprising;

a base member of insulating material having a front face and a rearface,

a switch mounted in the front face including,

first and second fixed contacts,

a movable contact biased into engagement with the first fixed contactand magnetically responsive to engage the second fixed contact,

a cam rotatably mounted on the front face,

a post secured to the base member and projecting perpendicularly fromthe front face,

a sleeve rotatably mounted on the post, a

a cam follower mounted on the sleeve and biased into engagement with thecam,

an auxiliary armature member on the base member displaced from theswitch,

a spiral bimetal element secured at one end to the sleeve and disposedin a plan parallel to the base,

a magnet carried by the free end of the bimetal element for movementbetween the switch and the auxiliary armature in response to ambienttemperature variations to actuate the movable contact of the switchbetween the first and second fixed contacts,

a resistor on the base member electrically connected in series with thesecond fixed contact of the switch for heating the bimetal element uponclosure of the movable contact with the second contact,

a plurality of bosses projecting from the rear face of the base member,

an opening in the base member through each of said bosses,

a resilient terminal clip of conductive material secured to each of saidbosses,

each of said terminal clips having an apertured cup-shaped portionoverlying the opening of the boss to which it is secured,

and a screw of conductive material threadedly mounted in the aperture ofthe cup-shaped portion of each of said terminal clips.

13. A control device as defined in claim 12 including;

a wall plate of insulating material secured to the rear face of the basemember and having a front face and a rear face,

a plurality of stepped terminal connectors of conductive materialmounted on the front face of the wall plate,

each of said terminal connectors comprising,

upper and lower horizontal portions connected by a vertical portion,

a threaded opening in each of said upper and lower portions,

the threaded opening in said upper portion of each of said connectorsbeing axially aligned with one of the apertured cup-shaped portions ofone of said terminal clips,

and the screw mounted in said one cup-shaped portion threadedly receivedin said threaded opening of the upper portion.

14. A control device comprising;

a base member of insulating material,

a switch mounted on the base member including,

first and second fixed contacts,

a movable contact biased into engagement with the first fixed contactand magnetically responsive to engage the second fixed contact,

a cam rotatably mounted on the base member,

a post rigidly secured to the base member,

a sleeve rotatably mounted on the post,

a cam follower mounted on the sleeve and biased into engagement with thecam,

an auxiliary armature member on the base member displaced from theswitch,

a spiral bimetal element secured at one end to the sleeve and disposedin a plane parallel to the base,

a magnet carried by the free end of the bimetal element for movementbetween the switch and the auxiliary armature in response to ambienttemperature variations to actuate the movable contact of the switchbetween the first and second fixed contacts,

a resistor on the base member electrically connected in series with thesecond fixed contact of the switch for heating the bimetal element uponclosure of the movable contact with the second contact,

a wall plate secured to the base member,

heating control terminal connector, a power source terminal connector,and a cooling control terminal connector on the wall plate,

a conductor electrically connecting the resistor to the heating controlterminal,

a conductor electrically connecting the movable contact to the powersource terminal,

and a conductor electrically connecting the first fixed contact with thecooling control terminal.

15. A control device comprising;

a base member of insulating material,

electrical switch means on the base member,

a cam follower rotatably received on the shoulder,-

a bimetal element secured at one end to the post for operating theswitch in response to ambient temperature variations,

.a resilient spring washer mounted on the post between the cam followerand bimetal element for frictionally restraining the cam followeragainst rotation relative to the post,

and a cam rotatably mounted on the base member operatively engaging thecam follower for varying the temperature response of the switch means,

said cam follower and post being selectively rotatable relative to eachother for calibrating the position of the bimetal relative to the cam.

16. A control device as defined in claim 15 further comprising;

.an arcuate slot formed in the base member, a cut-oif lever forresiliently urging the free end of the bimetal away from the switchmeans, including; an apertured lug mounted on the rear face of the basemember, and a resilient arm member projecting through the arcuate slotinto the path of the free end of the bimetal to augment the openingforce of the bimetal. 17. A control device as defined in claim 16further comprising;

a lever arm extending from the cam follower,

a stop post projecting from the front face of the base member into thepath of movement of the lever arm upon rotation of the post and bimetal,

said lever arm engaging the stop post to permit relative rotationbetween the cam follower and bimetal to selectively vary the calibrationof the cam follower with respect to the bimetal.

18. A control device as defined in claim 10 including;

an anti-torque washer having an apertured concave portion received onthe post between the rotatable element and the cam follower,

a stop post projecting from the base member,

and a locking leg extending radially from the concave portion of theanti-torque washer and connected with the stop post to frictionallyrestrain the rotatable element against rotation when the cam follower isrotated relative to the bimetal.

19. A control device comprising;

a base member of insulating material,

a post rotatably secured to the base member,

a pair of heat anticipating resistance coils secured to the base memberon opposite sides of the post,

a contact Wiper blade rotatably mounted on the post and havingoppositely disposed arcuate wiper contacts electrically engaging theresistance coils,

a shoulder on the post,

an anti-torque washer having an apertured concave portion received onthe post between the shoulder and the contact wiper blades with the rimof the concave portion frictionally engaging the contact Wiper blades,

a stop post projecting from the base member,

locking leg extending from the concave portion of the anti-torquewasher,

a recess on the end of the locking leg interengaged with the stop postto prevent rotation of the antitorque washer relative to the post,

a magnetically responsive switch mounted on the base member,

a cam rotatably mounted on the base member,

a cam follower mounted on the shoulder and biased into engagement withthe cam;

a fixed armature member mounted on the base displaced from the switch,

a spring washer received in the post between the bimetal and camfollower frictionally restraining the cam follower against rotationrelative to the post and bimetal, and a lever arm projecting from thecam follower,

said lever arm being engageable with the stop post upon rotation of thepost and bimetal to permit selective relative rotation between the camfol- 20 '20. A control device as defined in claim 19 including; acut-off lever mounted on the base member having a resilient arm memberprojecting into the path of the free end of the bimetal to resilientlyaugment the force of the bimetal urging the magnet toward the stationaryarmature.

References Qited by the Examiner UNlTED STATES PATENTS 2,262,343 11/41Shaw 200122 3,046,375 7/62 Houser 200-122 3,051,001 8/62 Laviana et al.200122 3,068,333 12/62 Hewitt 20087 lower and bimetal for calibratingthe position 15 BERNARD A. GILHEANY Primary Examiner of the bimetalrelative to the cam.

7. A CONTROL DEVICE COMPRISING: A BASE MEMBER OF INSULATING MATERIAL, ASWITCH MOUNTED ON THE BASE MEMBER INCLUDING, FIRST AND SECOND FIXEDCONTACTS, A MOVABLE CONTACT BIASED INTO ENGAGEMENT WITH THE FIRST FIXEDCONTACT AND MAGNETICALLY RESPONSIVE TO ENGAGE THE SECOND FIXED CONTACT,A CAM ROTATABLY MOUNTED ON THE BASE MEMBER, A POST RIGIDLY SECURED TOTHE BASE MEMBER, A SLEEVE ROTATABLY MOUNTED ON THE POST, A CAM FOLLOWERMOUNTED ON THE SLEEVE AND BIASED INTO ENGAGEMENT WITH THE CAM, ANAUXILIARY ARMATURE MEMBER ON THE BASE MEMBER DISPLACED FROM THE SWITCH,A SPIRAL BIMETAL ELEMENT SECURED AT ONE END TO THE SLEEVE AND DISPOSEDIN A PLANE PARALLEL TO THE BASE, AND A MAGNET CARRIED BY THE FREE END OFTHE BIMETAL ELEMENT FOR MOVEMENT BETWEEN THE SWITCH AND THE AUXILIARYARMATURE IN RESPONSE TO AMBIENT TEMPERATURE VARIATIONS TO ACTUATE THEMOVABLE CONTACT OF THE SWITCH BETWEEN THE FIRST AND SECOND FIXEDCONTACTS.